Blow molding method

A laminating blow molding method for making a hollow article, comprising:

• forming 1 to 500 fine holes per an area of 100 cm.sup.2 in a resin sheet by punching to thereby form projections as burrs on one side of the resin sheet, the diameter of the holes being between 0.1 mm and 1 mm;
• disposing the resin sheet between an outer surface of a parison extruded from a die and a mold so that said one side with the projections faces a cavity face of the mold;
• closing the mold so that the resin sheet is held between the cavity face of the mold and the outer surface of the parison;
• blowing the parison thereby laminating the parison to the resin sheet to form said hollow article, wherein during blowing, the resin sheet contacts the cavity face of the mold and air is released from between the parison and the resin sheet through the fine holes;
• heating the mold to a temperature exceeding a softening temperature of the resin sheet, the temperature being high enough to squash the fine holes by melting of the surface of the resin in contact with the mold so that the fine holes substantially do not remain in the resin sheet;
• cooling the mold;
• and
• taking out the hollow article.